Sounds like a messy situation -- I'm sorry your family is going through it... But SDN is not the place to find this information.
In terms of applying for medical schools, California is not a particularly advantageous state to be a resident of -- too many highly qualified applicants and too little in-state preference. So in short, this may not be a fight worth fighting. That said, you probably don't have time to become a legal resident of any other state, so CA it probably is. Mainly though, you'll just need to live somewhere and keep your legal US residency.
I'd look up what AMCAS says about international applicants, citizenship, green cards, permanent residency and state residency. Generally, all the information you need will be online and available, if not necessarily easily-decipherable. Start there, and follow up there with questions specific to your particular situation.